A. Field of the Invention
The present invention relates to self-propelled suction or vacuum cleaners and, more particularly, to a new and improved self-propelled, upright vacuum cleaner having a drive system for propelling the cleaner in forward or reverse directions with a minimum amount of effort.
B. Description of the Prior Art
One type of vacuum cleaner is an upright vacuum cleaner, sometimes referred to as an upright suction cleaner. The upright suction or vacuum cleaner has a base unit which is designed to be moved along a floor covering, such as carpeting. The vacuum cleaner includes an operating motor which drives an impeller to provide suction to a nozzle in the base unit so that dust and other particulate matter from the floor covering can be deposited in a disposable dust bag. The cleaner additionally includes a rotating agitator brush which also makes contact with the floor covering to assist in the cleaning operation.
In those cleaners that do not have an internal drive system, the cleaner is moved along the floor by an operator pushing or pulling on a handle pivotally connected to the base unit. A considerable amount of force may be required to push or pull the vacuum cleaner over carpeting, particularly high pile or deep shag type carpets. In addition, vacuum cleaners can be relatively heavy due to the weight of their operating motors and other components. Therefore, many vacuum cleaners have been provided with an internal drive system to assist an operator in propelling the cleaner in forward and reverse directions along a floor covering.
These so called self-propelled suction or vacuum cleaners may include an internal drive system that selectively couples the output of the vacuum cleaner motor to a pair of drive wheels on the base unit. Examples of such self-propelled vacuum cleaners are disclosed in U.S. Pat. Nos. 4,249,281; 3,618,687 and 4,347,643. Typically, the internal drive system is placed in either a neutral or inoperative mode whenever the drive wheels are not to be driven or in an operative mode whenever the drive wheels are to propel the cleaner in a forward or reverse direction. The modes of the drive system are determined by the movement of a slidable handle grip on the distal end of the handle. For example, when an operator pushes on the handle grip, the cleaner is propelled in a forward direction by the drive wheels. If the operator pulls back on the handle grip, the drive wheels will be driven in the opposite or reverse direction. Alternatively, the handle grip can be positioned such that the drive system will be maintained in its neutral mode. The handle grip can be coupled to the drive system by a Bowden cable which extends from the handle grip along the handle to the drive system. One such type of vacuum cleaner having such a handle grip and cable arrangement is disclosed in U.S. patent application Ser. No. 663,737, filed on Oct. 22, 1984, now U.S. Pat. No. 4,624,027, issued Nov. 25, 1986, and assigned to the assignee of the present application.
In previously designed self-propelled upright vacuum cleaners, the drive systems including the cleaner motors are disposed in the base unit. The transmissions forming a part of the drive system normally are mounted integrally with or directly on the axle of the drive wheels being driven. However, there is often only a limited amount of space available to mount the drive system in the base unit. Moreover, it is desirable to ensure that the drive wheels are not driven when the handle is placed in its upright position so that the cleaner is not inadvertently propelled. In previously designed cleaners, this was accomplished by adjusting the neutral position of a clutch so that it was placed in its neutral position whenever the cleaner handle was in the upright position. However, it is desirable to provide a positive locking mechanism to force the clutch into a neutral position whenever the handle is placed in its upright position.